The booking scheme of "Sevastopol" at the time of commissioning seems to be well known, but, oddly enough, not a single source contains a complete and consistent description.
Citadel
The basis of the vertical protection was a 225-mm armor belt with a length of 116.5 m, but the information about its height differs: either 5.00, or 5.06 m. It is reliably known that the upper edge of the armor belt reached the middle deck. Most sources indicate that with the normal displacement of the ship, the main armor belt rose above the water by 3.26 m. Accordingly, it went under the water by 1.74 or 1.80 m, depending on which height of the armor belt is correct. But dear S. E. Vinogradov in "The Last Giants of the Russian Imperial Fleet" gives a diagram according to which the height of the armor plates of the battleships of the "Sevastopol" type was 5, 06 m, while in the normal displacement above the water should be 3.3 m, and below the waterline, respectively, 1, 73 m.
Along the length, the main armor belt completely covered all the engine and boiler rooms, as well as the main caliber artillery barbets, there are no discrepancies in the sources. Most of them also indicate that the 225 mm belt was closed at the bow and stern by 100 mm traverses that formed the citadel. But here A. Vasiliev in his book "The first battleships of the Red Fleet" for some reason asserts that "Special armored traverse transverse bulkheads were not provided."
Extremity Reservation
In the bow and stern, the main armor belt continued with armor plates of the same height, but 125 mm thick. Everything seems to be clear, if not for the "Scheme of armoring of the battleship" Sevastopol "", compiled on the basis of the materials of the Russian State Archive of Naval Aviation, given in the monograph by A. Vasiliev.
On it you can see that between the 225-mm armor of the citadel and the 125-mm armor belts of the extremities there are some "transition plates" whose thickness is not indicated. It can be assumed that the thickness of these slabs was also "transitional", that is, it was less than 225 mm, but more than 125 mm.
All sources agree that the bow was fully booked, up to the stem, but there are ambiguities about the stern. Presumably, this was the case here: behind the barbet of the 4th turret of the main caliber of the Sevastopol-class battleships there was a tiller compartment. From the sides of the ship, it was protected by a 125-mm armor belt, and from the stern - by an inclined traverse 100 mm thick. According to A. Vasiliev, this traverse was 125 mm thick in the hold. So, apparently, the 125-mm armor belt continued until this armored traverse, leaving the last few meters of the stern unprotected. On the other hand, the above "Scheme" seems to hint that the side still had 50 mm armor in this area. this area has been thickened to 38 mm.
Upper Armor Belt
There are also some ambiguities with him. It is reliably known that the upper belt began from the stem of the ship, but its height is not clear - usually 2, 72 m is indicated, but the author also came across a figure of 2, 66 m, and S. E. Vinogradov - even 2, 73 m. The upper belt protected the space from the upper to the middle deck, while above the citadel it had a thickness of 125 mm, and above the 125-mm armor plates of the extremity - 75 mm. It did not continue to the stern of the citadel, so from the edge of the barbette of the 4th tower to the sternboard of the Sevastopol-class battleships between the upper and middle decks, they had no protection.
But with traverses at the level of the upper belt, everything is not at all easy. But this issue should be dealt with in conjunction with the booking of barbets.
Anti-splinter armor bulkheads
Everything seems to be simple here. Behind the upper 125 mm armor belt, between the upper and middle decks, the Sevastopol-class battleships had additional protection in the form of 37.5 mm bulkheads, and behind the main 225 mm armor belt, between the middle and lower decks, there were 50 mm thick bulkheads. Taking into account that 50 mm bulkheads and 225 mm armored belts were connected from the lower edge by armored bevels, it turned out that the most important parts of the ship had two-layer protection.
Unfortunately, there were some inconsistencies in the sources. So, A. Vasiliev points out that the longitudinal anti-fragmentation bulkheads went along the entire length of the main armor belt. However, the schemes cited by him refute this statement. According to them, only 50 mm bulkheads went along the entire length of 225 mm of the armor belt, and 37.5 mm were shorter - they did not adjoin 100 mm traverses, but only to the barbets of the 1st and 4th turrets of the main battery.
Thus, if the 225-mm belt and the 50-mm bulkhead behind it protected the supply pipes of the bow and stern turrets of the main battery, then the 37.5 mm armor bulkhead did not. But this, again, if it is the scheme that is correct, and not the statements of A. Vasiliev.
Barbetts and traverses
Reservations for barbets are also very controversial. It is reliably known that above the upper deck, the barbets of the 1st, 2nd and 3rd turrets of the main battery had 150 mm of armor. At the same time, almost all sources claim that the 150 mm section ended precisely on the upper deck, and below, between the upper and middle decks, the thickness of the barbet of the 2nd and 3rd main turrets was only 75 mm.
However, if you look at the schemes of battleships, you get the impression that the 150-mm section of the barbet still did not end at the level of the upper deck, but continued a little further down so that a projectile that hit the upper deck armor at an acute angle and pierced it would hit in 150 mm armor plate.
Whether it is true or not, the author does not know for certain. Likewise, nowhere is the thickness of the barbette's protection from the middle deck and below indicated.
But, in any case, the protection of the barbets of the 2nd and 3rd towers of the main battery is more or less clear: it is a 150-mm "ring" near the tower, then somewhere, but not below the upper deck, decreasing to 75 mm and having such thickness down to the middle deck, and possibly beyond. I must say that the barbets of these main battle towers in the space between the upper and middle barbette decks were protected quite well. In order to get to the feed pipe at this level, the projectile needed to pierce the 125-mm upper belt, then 37.5-mm fragmentation bulkhead and then another 75-mm barbet, and in total - 237.5 mm of spaced armor.
Another thing is the 1st and 2nd turrets of the main caliber. As mentioned above, judging by the diagram, the 37.5-mm armored bulkheads were adjacent to the rear side of the barbets: for the 1st main battery turret - in the part facing the stern, for the 4th main battery turret - respectively, to the bow. Thus, between the upper and middle decks, the supply pipes of the bow and stern turrets of the main battery protected only 125 mm of the upper armored belt and 75 mm of the barbette, and only 200 mm of spaced armor. But further in the bow the upper armor belt had only 75 mm, and in the stern it did not continue at all! To compensate for this weakness, the part of the barbet of the 1st tower, facing the bow, was thickened to 125 mm, and the part of the barbet of the 4th tower, facing the stern, up to 200 mm thick. Thus, from the fore and aft angles, these towers were also protected by 200 mm of armor, the only difference was that in the bow it was a 75 mm armor belt and a 125 mm barbet, and in the stern - 200 mm barbet. In fact, we can say that the barbet of the 4th main battery turret from aft angles received the best protection - nevertheless, the 200 mm armor plate had greater durability than the spaced armor of 125 + 75 mm. At the same time, judging by the diagrams, the part of the barbet of the 4th tower, towering above the upper deck and facing the stern, also had a thickness of 200 mm, in contrast to the 150 mm of the other three main turrets.
Here, however, a question arises. The fact is that the stern 100-mm traverse, most likely, protected the supply pipe of the 4th main turret only up to the level of the middle deck. And, since the section of the barbet, which had a thickness of 200 mm, had a very limited area, and the rest of the barbet of the 4th main tower tower had the same 75 mm, then it seemed like a whole "gate" was obtained - the projectile could fly under the upper deck and hit 75 mm barbet. The sources do not give a direct answer to this question, but the diagram shows a 125 mm traverse connecting the edge of the upper armored belt and a section of 200 mm of the barbet reservation.
Most likely, it really existed, although there is no mention of it in the sources, in this case the 75-mm area of the barbette of the main turret aft tower was protected by the same 200 mm of spaced armor.
Let us now consider the protection of the supply pipes of the main caliber towers below, between the middle and lower decks. Here everything is more or less clear only with the 1st and 4th main battery towers. It turned out that their supply pipes were, as it were, in boxes formed from the bow (stern) by 100 mm traverse, and along the sides - by 50 mm armored bulkheads. Accordingly, even if this section of the supply pipe did not have its own reservation, then from the bow angles it was covered with 125 mm armored belt of the extremity and 100 mm of traverses, and along the sides - 225 mm main armor belt and 50 mm armored bulkhead, that is, 225 and 275 mm spaced armor accordingly. At the same time, it should be noted that the traverse and 125-mm armor plates that protected the bow of the ship were located at an angle close to 90 degrees, so that it would be rather difficult to pierce them even for a 305-mm projectile.
But the 3rd and 4th turrets of the main battery were located closer to the middle of the ship, where the hull of the Sevastopol-class battleships, of course, was much wider, and the 50 mm armored bulkheads were at a considerable distance from the feed pipes. If they really did not have armor protection, then the enemy projectile had to overcome to defeat them either a 225-mm belt and a 50-mm bulkhead (bevel), or a 125-mm upper belt, a 37.5-mm bulkhead and a 25-mm deck or 37, 5 and 25 mm armored deck, which, in general, also cannot be called quite bad protection.
Completing the description of the vertical armoring of the hulls of these Russian battleships, we note that they did not have separate casemates, since they were "combined" with the upper armored belt 125 mm thick. In addition, there were 25- or 25.4-mm armored bulkheads between the guns … But here, too, not everything is clear. The diagram indicates that such traverses separated each gun from each other, but sources contain information that in one fenced casemate there were 2 guns each. In general, running a little ahead, we can say that the anti-mine caliber "Sevastopol" was placed in casemates with frontal armor 125 mm, roof 37, 5 mm, armored bulkheads 25, 4 mm and deck 19 mm.
Horizontal booking
Everything is comparatively simple here, but at the same time it is here, perhaps, that contains the "main ambiguity" in the booking of battleships of the "Sevastopol" class.
The upper deck was the basis of horizontal armor protection and consisted of 37.5 mm armor - everything is clear here, and there are no discrepancies in the sources. The middle deck was considered splinterproof - it had a thickness of 25 mm (more likely still 25.4 mm - that is, an inch) all the way between 50 mm armored bulkheads and 19 mm - in the sections between 125 mm upper armored belts and 50 mm splinterproof bulkheads on the left and right sides … The lower deck in the horizontal part was not armored at all - here it was formed by 12 mm steel flooring. But the lower deck also had bevels, they were armored, but … the thickness of this armor remains a mystery.
The greatest thickness of these bevels is given by I. F. Tsvetkov and D. A. Bazhanov in his book “Dreadnoughts of the Baltic. Battleships of the "Sevastopol" type in the First World War and the Revolution (1914-1919) ". They claim that the bevels of the first Russian dreadnoughts were 50mm armor plates stacked on a 12mm steel deck. Many other historians, for example E. S. Vinogradov and A. Vasiliev indicate that the total thickness of the armor of the lower deck bevels at the Sevastopol was 50 mm. But at the same time, in the same monograph by A. Vasiliev, on the "Scheme of booking the battleship" Sevastopol "", it is shown that these bevels consisted of 25 mm armor plates laid on 12 mm flooring (more likely 25, 4 mm armor for 12, 7 mm become). The author of this article has been trying for a long time to find copies of the drawings that could unambiguously answer the question about the thickness of the bevels of the "Sevastopol". Unfortunately, the copies available on the Internet do not have sufficient resolution - the numbers we are interested in are on them, but they are illegible.
Other armor protection
The conning towers of the Sevastopol-class battleships had the same armor: walls - 254 mm, roof - 100 mm, and floor - 76 mm. The armored pipes protecting the wires were 125 mm thick in the conning tower and 76 mm outside them (which is somewhat strange). The towers were armored as follows: forehead and sides - 203 mm, roof - 76 mm, aft armor plate - 305 mm. With the casings of chimneys, alas, it is unclear. As far as can be judged, they had 22 mm armor protection between the upper and middle decks. But, judging by the booking schemes, above the upper deck and approximately along the height of the barrels of 305-mm guns (on direct fire), they had protection of either 38, 5 mm, or 75 mm.
Between the wars
Without a doubt, the armor protection of the first domestic dreadnoughts of the "Sevastopol" type left much to be desired. But still, she was not so "cardboard" as it is commonly believed today - Russian ships were armored better than the British "Admiral Fischer's cats", but worse than the Moltke-class battle cruisers. In general, the protection of "Sevastopol" against the 280-305-mm shells of the guns of the First World War can be considered quite acceptable. The problem, however, was that by the time our dreadnoughts entered service, the leading naval powers were already building battleships with much more powerful 343-mm, 356-mm and even 380-381-mm guns.
In principle, the protection of the Sevastopol-class battleships could still hold out against semi-armor-piercing 343-mm shells with their almost instant fuse, which were revered by many in the Royal Navy as the main weapon of dreadnoughts and battle cruisers. But by the end of the First World War, the British realized their delusions and created normal, full-fledged armor-piercing shells. The Germans had those initially.
We can say that according to the results of the First World War, almost all the leading fleets of the world have finally created first-class armor-piercing shells for the 343-410-mm guns of their newest battleships. Against such ammunition, the armor of "Sevastopol" at the main battle distances did not protect at all.
In addition, in the interval between the world wars, the capabilities of naval aviation significantly increased, including the weight of the bombs that it could drop on warships, which also required strengthening the horizontal armor protection of battleships.
Modernization of the armor protection of battleships in the interwar period
It was minimal. In fact, on the battleships "Marat" and "October Revolution" only the roofs of the main caliber turrets were reinforced - from 76 to 152 mm. The same was done for the towers of the Paris Commune, but this battleship also received a significant increase in horizontal booking: the 25.4-mm armor plates of the middle deck were removed, and in their place were installed 75-mm armor plates intended for the light cruiser Admiral Nakhimov ". This significantly improved the protection of the ship against both aircraft and enemy artillery. As the experience of the Great Patriotic War showed, the combination of 37.5-mm upper and 25.4-mm medium armored decks made it possible to quite successfully withstand hits of 250 kg of aerial bombs: they pierced the upper deck and exploded in the interdeck space, and the middle deck quite successfully reflected the fragments. Well, the "Paris Commune" had every chance to withstand even 500-kg bombs.
In addition, the battleship that crossed from the Baltic to the Black Sea received such an important tool as the boules. Strictly speaking, battleships of the "Sevastopol" type did not have any developed anti-torpedo protection, although a certain role could be played by the coal pits of ships located along the sides. But in the interwar period, the battleships were converted to liquid fuel, so that their "PTZ" became completely questionable. But the 144-meter "blisters" of the "Paris Commune" were supposed to provide protection against 450-mm air torpedoes containing 150-170 kg of explosives. Now it is hardly possible to say how correct these calculations were, but nevertheless, a significant increase in the PTZ of the Black Sea battleship is beyond doubt.
In addition, the appearance of boules on the Paris Commune made it possible to resolve the issue of the stability of the ship, which had significantly deteriorated due to the mass of additional weights installed above the waterline during the battleship upgrades. Vertical armor protection has also slightly improved. The fact is that part of the blister was located opposite the 225 mm armor belt along its entire height and had a steel wall 50 mm thick. Of course, 50 mm of steel (although it is possible that it was armor) could not significantly increase the protection of the battleship, but still, there was a small increase.
There was one more innovation related to the armor of these ships. Since the battleships of the "Sevastopol" type did not amaze the imagination with their seaworthiness, it was decided to install special bow attachments on them, which would reduce the flooding of the main turret bow at high speed, or in fresh weather. To compensate for the weight of the cladding, several 75 mm armor plates of the upper belt were removed from the noses of all three Soviet battleships (on the Marat, for example, over 0-13 frames). The hole in the defense was compensated for by the installation of a traverse, which had a thickness of 100 mm for the "Marat" and 50 mm for the "October Revolution", but there was no data on the "Paris Commune". But all this, of course, had nothing to do with strengthening protection.
conclusions
Without a doubt, the most important reason for the limited modernization of the armor of Soviet battleships was the general lack of funds that the young Land of the Soviets could afford to spend on its navy. But you need to understand that even if the leadership of the USSR was bathed in money, no technical tricks could have provided protection for ships that were originally designed for a normal (not even standard!) Displacement of less than 23,000 tons from the then-modern armor-piercing shells of 356-410 caliber mm. From the point of view of price and quality, the modernization of the Paris Commune looks optimal: the increase in horizontal booking and boules looked really useful innovations. One can only regret that the USSR did not find the means for a similar defense of "Marat" and "October Revolution". Of course, the Baltic battleships did not have the opportunity to show themselves to some extent in the Great Patriotic War, but if the Marat had received a 75-mm armored deck, perhaps it would have survived during the fatal raid of German aviation, which took place on 23 September. 1941 g.
